Improved multifeed circular knitting machine equipped with pneumatic yarn trappers

ABSTRACT

A multifeed circular knitting machine with a striper at each feed. Each striper includes fingers to present yarns and withdraw them from needles, and a cutter device for severing a withdrawn yarn. A yarn holder block, between each striper and its cutter device, holds a withdrawn and severed yarn until next required. Each yarn holder block has a through-aperture open at one end adjacent to a path taken by a withdrawn yarn and in communication at its opposite end with air suction. Air suction is produced by a fan unit common to all the stripers.

United States Patent Inventor Walter Goadby Evington, Leicester, England Appl. No. 780,377 Filed Dec. 2, I968 Patented Mar. 23,1971 Assignee I Camber International (England) Limited Leicester, England Priority Dec. 16,1967

Great Britain 57,235/67 IMPROVED MULTIFEED CIRCULAR KNITTING MACHINE EQUIPPED WITH PNEUMATIC YARN TRAPPERS 8 Claims, Drawing Figs.

U.S. Cl 66/ 140, 66/ 145 Int. Cl..- D04b /61 Field of Search 66/ (S),

168 (Cursory), (S)

[56] References Cited UNITED STATES PATENTS 3,050,970 8/1962 Billi 66/140(S) 3,157,036 11/1964 Coile 66/140(S) FOREIGN PATENTS 1,057,227 2/1967 Great Britain 66/140(S) 1,110,607 4/1968 Great Britain 66/ 168 Primary Examiner-Robert R. Mackey Attorney-Larson, Taylor and Hinds ABSTRACT: A multifeed circular knitting machine with a striper at each feed. Each striper includes fingers to present yarns and withdraw them from needles, and a cutter device for severing a withdrawn yarn. A yarn holder block, between each striper and its cutter device, holds a withdrawn and severed yarn until next required. Each yarn holder block has a through-aperture open at one end adjacent to a path taken by a withdrawn yarn and in communication at its opposite end with air suction. Air suction is produced by a fan unit common to all the stripers.

IMPROVED MULTWEED CIRCULAR KNITTING MACHINE EQUIPPED WITH PNEUMATIC YARN TRAPPERS This invention relates to multifeed circulate knitting machines of the kind equipped, at 'each feed, with a yarn supplying and changing mechanism.

' By the expression a yarn supplying and changing mechanism" is meant a mechanism which comprises, in combination, a plurality of individually movable and selectable yam fingers, in the nature of yarn placers, arranged side by side and each adapted, when moved into its operative feeding position, to guide and feed to the needles at least one yarn or thread (hereinafter for convenience and simplicity referred to as "a yarn) and, when rendered inoperative by movement to a nonfeeding position, to withdraw the said yarn or yarns from knitting, means for effecting selective actuation of the fingers whereby a yarn or yarns can be substituted for another or others at the feed, according to pattern requirements, a cutter device for automatically severing each yarn withdrawn from knitting and means for holding the free end or ends of the yarn or yarns so severed and thereby retaining such yarn or yarns threaded through the relevant feeding finger while the latter remains inoperative. I

So ,far as the present invention is concerned, it is primarily the intention that the fingers of each of the yam-supplying and changing mechanisms shall be threaded with yarns of respectively different colors so that the mechanism is employed as a horizontal striper. Accordingly, while for convenience in the following further description and in the appended claims, such a mechanism will hereinafter be referred to as a"striper,

there is no limitation in this respect as other classes of yarn change are also envisaged.

Again, when it is stated in this specification that a striper is provided at each feed of the machine, it is intended that this phrase shall be sufiiciently wide as to include fat every feed as well as at each appropriate feed of a plurality of feeds less than the total number provided.

A multifeed circular knitting machine of the kind herein referred to is capable of producing tubular piece goods, and as one typical example of such a machine may be quoted a single jersey machine.

Now heretofore the cutter device of each striper, in a circular knitting machine of the kind concerned, has usually had in association therewith a mechanical yarn trapper designed to trap the free end of a yarn withdrawn from knitting and severed by the cutter device and to hold such yarn inactive until it is again required to be fed to the needles. A mechanical trapper comprises a fixed part and a relatively movable clamping element formed to present opposed trapper faces between which a yarn can be clamped and held, the parts of the trapper usually being sprung together.

A mechanical trapper is not a very practical device in a case where, say, two dissimilar yarns simultaneously withdrawn from knitting require to be trapped together. By the expression dissimilar" yarns is meant yarns which differ from one another as regards denier or count, composition (natural or manrnade), spinning, nature and degree of twist, bulking, doubling, and so on. I 7

Accordingly, the primary object of the present invention is to provide, in a multifeed circular knitting machine of the kind herein referred to, improved, simple and efiicient means for holding in a controlled fashion the freeends of severed yarns withdrawn from knitting.

A particular aim is to enable yarns of dissimilar types and/or deniers or counts simultaneously withdrawn from knitting to be effectively held until again required to be fed to the needles.

According to this invention there is mounted on the striper at each feed of the machine an apertured yarn holder block, which is located between the striper and its cutter device, in a path taken by yarn in the course of being withdrawn from knitting at the striper, the said block having extending right through it an aperture which is open at one end adjacent to the said yarn path and at the opposite end is arranged in communication with a source of continuous air suction.

The idea is that whenever a yarn withdrawn from knitting is automatically severed by the cutter device of the relevant striper, the free end of that yarn, still threaded through a finger which has been moved to its nonfeeding position will, by pneumatic action, be sucked into the open end of the aperture in the yarn holder block andheld there. Thus, the said block may be regarded as a "trapper" block in which the free end or ends of a severed yarn or yarns is or are trapped." It will, however, be readily understood that the free end of each severed yarn is not in any sense actually clamped, but is merely drawn into the aperture and retained therein by pneumatic power. Conversely, whenever a pneumatically held inactive yarn is again required to be fed to the needles, all that is necessary is for the finger through which the yarn is threaded to be moved into its operative, i.e. yarn-feeding position, as a result of which the yarn will be taken and knitted by the needles in aperture in the yarn holder block and thereby released from the stream of inflowing air.

.In carrying out the invention, there is preferably provided a single source of air suction common to all of the stripers.

In order that the invention may be more clearly understood and readily carried into practical effect, a specific constructional example thereof will now be described with reference to the accompanying drawings, wherein:

FIG. 1 is a vertical sectional view of so much of the head of a multifeed circular knitting machine as is necessary to illustrate the application thereto of a stripper fitted with an apertured yarn holder block;

FIG. 2 is a fragmentary plan view, with some parts omitted for clarity, showing the layout of a multiplicity of the stripers and their apertured yarnholder blocks;

FIG. 3 is a front end view of one of the yarn holder blocks as seen from the outside of the needle cylinder, looking inwards, and shown in relation to the linear path followed by the heads of needles in the course of being retracted at a knitting location;

FIG. 4 is a general perspective view of one of the apertured yarn holder blocks per se;

FIG. 5 is a vertical section view of the said block taken on the line V-V of FIG. 4,

FIG. 6 is a cross-sectional view of the same block taken on the line VI-Vl of FIG. 4;

FIGS. 7, 8 and 9 areperspective views of a yarn holder block shown in three respectively different operational situations hereinafter to be described; and

FIG. 10 is a schematic layout, as seen in elevation, of the common suction air supply to the multiplicity of apertured yarn holder blocks.

Referring to FIGS. l, 2 and 10, the head of the illustrated circular knitting machine designated generally by the letter l-l, comprises a rotary needle cylinder 1 equipped with independent latch needles such as 2, and a sinker bed 3equipped with outside 'sinkers 4 cooperable with said needles. At 5 is indicated the conventional sinker cap which, as shown in FIG. 1, carries cams, such as 6, for action upon the sinker butts 4a. The sinker cap 5 is rabbetted at 5a to locate a ring 7 serving to carry the striper boxes 8, i.e. the main bodies or brackets of the stripers as hereinbefore defined.

In FIG. 10 the bed plate of the machine, supported upon the legs 9 of the latter is indicated at 10, whereas the numeral 11 designates the conventional bobbin ring supported on vertical posts or columns 12.

Each of the stripers, one per feed, includes a plurality of selectable yarn striping fingers (yarn placers) 13 arranged side by side, as shown in FIG. 2. Each such finger I3 is adapted, when moved into its operative feed in position to present a portion Y of its yarn Y across the needle path up (see FIG. 8) and, when rendered inoperative, by movement to a retired nonfeeding position (FIG. 7), to withdraw the said yarn a from knitting. Conventional means of any appropriate character (not shown) are provided for effecting selective actuation of the striping fingers 13 whereby one yarn can be substituted for another. Each striper also includes an automatically operable cutter device 14 for severing any yarn withdrawn from knitting. This device 14 is of known form comprising a fixed cutter blade 14a and a relatively movable blade 14b. In FIG. 9, the device 14 is shown as it appears immediately prior to being operated to sever the portion Y of the yarn Y just withdrawn from knitting. The movable cutter blade 14b is engaged in a recess formed in part 15b of link 15 by means of which it is operated the link being actuated by a cam (not shown) under the sinker ring. As depicted in FIG. 1, this link is made in two relatively adjustable parts 15a and 15b secured together at 16, to permit of precise setting of the blade 14b.

Each striper, moreover, essentially includes means for holding the free end of a yarn so severed and thereby retaining the said yarn threaded through the relevant striping finger 13 while the latter remains inoperative in its retired, i.e., withdrawn, position. In accordance with the characteristic feature of the present invention, these holding means forming part of the striper at each feed consist of an apertured yarn holder block 17. The block 17 is provided with an upstanding lug 17a having formed therein tapped holes 17b to receive screws 18 by means of which the said block is rigidly secured upon an inwardly directed extension 8a at one side of the striper box 8. The yarn holder (trapper) block 17, which is located between the striper box and its cutter device 14, has extending right through it an aperture 170 (FIGS. 5 and 6) which aperture is open at one end to provide an orifice 17d into which the free end of a severed yarn can be sucked and at the opposite end is arranged in communication with a source of continuous air suction.

Incidentally, there is secured to each striper box 8 a latchguard 19, the operative portion 190 of which is disposed immediately below and adjacent to the relevant yarn holder block 17.

In the illustrated example, the orifice 17d in each yam holder block 17 is in the form of a relatively narrow slot designed to increase the flow of ambient air into the aperture 170 and thereby commensurately reduce the volume of flowing air required to produce the degree of pneumatic (suction) power for the intended purpose,- A slot about five-eighths inches long and 0.050 inches wide is found to be sufficient. The relatively narrow slot 17d with its opposed, sides advantageously leads into a cylindrical hole 17:: constituting the remaining portion of the single through-aperture in the block. The outer end of the block is formed around the cylindrical hole with a boss 17f on to which can be fitted the lower end of a flexible air tube 20. It is preferred that there shall be no abrupt change in the flow of air from the narrow slot 17d into the cylindrical hole 17e; to avoid any such change, a smoothly contoured aerodynamic surface s between the opposite end portions of the aperture 170 is envisaged. Such a contoured surface s may be achieved by a moulding technique if, as may be, the yarn holder block 17 is moulded in a suitable plastic material.

In any event, it is very important that the relatively narrow slot 17d in the yarn holder block 17 of each striper 8 shall lie closely adjacent to the path p (FIG. 9) taken up by a yarn Y in the course of being withdrawn from knitting. In this way a severed yarn will initially be longitudinally drawn by the air suction lengthwise of the slot 17d, thereby enabling the free end of the yarn as it comes opposite to the slot to be easily turned and sucked through it into the aperture where it is thereupon loosely retained in the path of the inflowing air.

The relatively narrow slot 17d constituting the orifice into the aperture 17c is downwardly inclined at a location a little above the knitting line, i.e. an imaginary line kl (see FIG. 3) connecting the heads 2a of needles 2 in the course of being retracted by the stitch cam at the relevant feed. As will be seen, the angle of the orifice 17d with reference to the horizontal is less steep than the inclination of the knitting line kl.

To ensure that a yarn Y, as and when withdrawn from knitting by a movement of the relevant striping finger 13 to its retired nonfeeding position, is maintained closely adjacent to the downwardly inclined slot 17d, the yarn holder block may be, as shown, formed or provided immediately above and along the upper edge of the said slot with a protuberant guide ledge 21 beneath with a straight length Y of the yarn Y is drawn by the needle last to knit it.

As will be appreciated, it is at a point beyond the lowest end of the relatively narrow slot 17d that the cutter device 14 of each striper is located. The distance between the cutter device and the said slot must, in fact, be sufficient to permit a withdrawn stretch of, say, bulked, e.g. crimped, yarn, when severed, to relax and yet still have its free end within the influence of the stream of air flowing into the slot.

Referring again to FIG. 7, it will be seen that the striping finger 13 is in its retired nonfeeding position, with the free end of the withdrawn yarn Y, still threaded through the said finger, extending inwardly through the narrow slot 17d into the aperture 170 in the yarn holder block 17.

In FIG. 8 the finger 13 is in its operative, i.e. yarn-feeding, position in which it presents a portion Y of the yarn across the needle path np. As a consequence, the needles, such as that indicated at 2, receive the yarn into their hooks and knit it.

FIG. 9 illustrates the conditions which apply immediately following the upward swing of a finger 13 into its nonfeeding position to withdraw the yarn from knitting and just prior to severance of the yarn by the cutter device 14. As will be seen, a portion Y of the yarn is drawn beneath ledge 21 so that it extends along the length of the narrow slot or orifice 1711.

In each of FIGS. 7, 8 and 9 the sinker path is indicated at sp.

Unless an appropriate measure is taken to prevent it, there may be a tendency for certain yarns, when withdrawn from knitting by uncontrolled upward swinging movements of the striping fingers 13, to be pulled up to such an extent that their free ends fail to be drawn into the narrow slots 17d. To guard against this eventuality, there is provided in the illustrated example, above the striping fingers of each striper a restrictor bar 22, preferably rubber or similarly covered, which is so located as to restrict the upward swing of any one of the striping fingers in the course of it being moved into its retired nonfeeding position. Such a restrictor bar may, in fact, and as shown, actually serve to determine the nonfeeding positions of the fingers. As will be seen in FIG. 1, the said bar is secured to and carried by the inwardly directed extension at one side of each striper box 8.

The yarn holder block 17 of each striper may alternatively be carried by an initially separate plate which is attached to the striper bracket. Or the striper box or bracket may itself be formed integrally with a yarn holder block. As to each cutter device, this may be mounted either upon a suitable extension of the corresponding yarn holder block or upon an adjacent independent stationary part of the machine.

As previously mentioned, it is preferable to provide, a single source of air suction common to all of the stripers. Thus, such an arrangement is illustrated in FIG. 10 wherein an air conduit in the form of a flexible tube 20 extends upwardly from each of the yarn holder blocks 17. For clarity of illustration only two of the whole circular series of blocks 17 are shown in FIG. 10. The lower end portion of each flexible air tube 20 is fitted over the boss 17f of the relevant yarn holder block 17 so that the tube is in communication with the through-aperture 17c in the said block. At its upper end each air tube 20 is connected with, and communicates with the interior of, a central air chamber 23 mounted in a fixed position above the knitting head H of the machine, this chamber being in turn connected, through the medium of a horizontally disposed rigid pipe 24 and a vertically disposed flexible hose 25, with a common source of air suction in the form of a fan unit 26 which is arranged to be driven by a coaxial electric motor 27 and has combined with it a coaxially disposed air filter unit 28. The

motor 27 is supported from the'framework of the machine. The central air chamber 23 is of truncated conical form, i.e. of inverted funnel shape, being closed at its underside by a leakproof bottom cover 23a into holes in which are fitted the upper ends of the flexible air tubes extending upwardly from the individual yarn holder blocks l7.'The upper end of the central air chamber 23 is formed with a cylindrical hollow boss or extension 23b which extends up through a central hole yarns can be threaded, each of said fingers being capable of movement to an operative position to guide and feed a yarn to the needles and also of reverse movement to a nonfeeding position to withdraw said yarn from knitting; a cutter device for severing the yarn when so withdrawn; and means for holding the free end of the severed yarn to retain it threaded through the finger while the latter remains inoperative; said machine being characterized in that the yarn holding means combined with each yam-supplying'and changing mechanism comprises a block which is located between the said mechanism and its cutter device, in a path taken by a yarnin the course of being withdrawn from knitting, said block having formed right through it an aperture which is open at one end adjacent to the aforesaid path and at its opposite end is arranged to be in communication with a source of air suction, the open end of the said aperture being in the form of a relatively narrow slot which is adapted to increase the flow of ambient air into the aperture and is downwardly inclined at a location above a line connecting the heads of needles being retracted for knitting at the relevant feed, the angle of the slot with reference to the horizontal being less steep than the inclination of the aforesaid line, andthe machine also being characterized in that each yarn holder block is provided, immediately above and along the upper edge of the downwardly inclined narrow slot, with a protuberant guide ledge beneath by pneumatic action, by initially longitudinally drawn by the air suction lengthwise of the said slot and so readily sucked into the aperture and held therein.

2. A multifeed circular knitting machine according to claim 1, wherein the saidnarrow slot in each yarn holder block has opposed sides and leads into a cylindrical hole constituting the remaining portion of the through-aperture in the block. 3. A multifeed circular knitting machine according to claim 2, wherein a smoothly contoured aerodynamic surface is provided between the-opposite end portions of the through-aperture in each yarn holder block to ensure that there is no abrupt change in the flow. of air from the-narrow slot into the cylindrical hole.

4. A multifeed circular knitting machine according to claim 1, wherein there is provided above the yarn fingers of each yarn-supplying and changing mechanism a restrictor bar so located-as to restrict an upward swing of any one of the fingers in the course of being moved into its nonfeeding position, thereby ensuring that the free end of the relevant withdrawn and severed yarn is drawn into the aperture in the corresponding yam-holding block. v

S. A multifeed circular knitting machine according to claim 1, wherein there is provided a single source of air suction common to all of the yarn-supplying and changing mechanism.

6. A multifeed circular knitting machine according to claim 5, wherein air-conducting pipes, one in communication with the through-aperture in each of the yarn holder blocks, extend upwardly and at their upper ends are connected to, and communicate with the interior of, a central air chamber which is mounted above the knitting head of the machine and is in turn connected with the commonsqurce of air suction.

7. A multtfeed circular knitting mach ne according to claim i'uioas 0599' 

1. A multifeed circular knitting machine which includes: a needle cylinder; needles in said cylinder; and, at each feed, a yarn supplying and changing mechanism comprising, in combination, a plurality of individually movable and selectively operable yarn fingers arranged side by side and through which yarns can be threaded, each of said fingers being capable of movement to an operative position to guide and feed a yarn to the needles and also of reverse movement to a nonfeeding position to withdraw said yarn from knitting; a cutter device for severing the yarn when so withdrawn; and means for holding the free end of the severed yarn to retain it threaded through the finger while the latter remains inoperative; said machine being characterized in that the yarn holding means combined with each yarn-supplying and changing mechanism comprises a block which is located between the said mechanism and its cutter device, in a path taken by a yarn in the course of being withdrawn from knitting, said block having formed right through it an aperture which is open at one end adjacent to the aforesaid path and at its opposite end is arranged to be in communication with a source of air suction, the open end of the said aperture being in the form of a relatively narrow slot which is adapted to increase the flow of ambient air into the aperture and is downwardly inclined at a location above a line connecting the heads of needles being retracted for knitting at the relevant feed, the angle of the slot with reference to the horizontal being less steep than the inclination of the aforesaid line, and the machine also being characterized in that each yarn holder block is provided, immediately above and along the upper edge of the downwardly inclined narrow slot, with a protuberant guide ledge beneath which a length of yarn can be drawn by the last needle to knit it, whereby the free end of a withdrawn and severed yarn can, by pneumatic action, by initially longitudinally drawn by the air suction lengthwise of the said slot and so readily sucked into the aperture and held therein.
 2. A multifeed circular knitting machine according to claim 1, wherein the said narrow slot in each yarn holder block has opposed sides and leads into a cylindrical hole constituting the remaining portion of the through-aperture in the block.
 3. A multifeed circular knitting machine according to claim 2, wherein a smoothly contoured aerodynamic surface is provided between the opposite end portions of the through-aperture in each yarn holder block to ensure that there is no abrupt change in the flow of air from the narrow slot into the cylindrical hole.
 4. A multifeed circular knitting machine according to claim 1, wherein there is provided above the yarn fingers of each yarn-supplying and changing mechanism a restrictor bar so located as to restrict an upward swing of any one of the fingers in the course of being moved into its nonfeeding position, thereby ensuring that the free end of the relevant withdrawn and severed yarn is drawn into the aperture in the corresponding yarn-holding block.
 5. A multifeed circular knitting machine according to claim 1, wherein there is provided a single source of air suction common to all of the yarn-supplying and changing mechanism.
 6. A multifeed circular knitting machine according to claim 5, wherein air-conducting pipes, one in communication with the through-aperture in each of the yarn holder blocks, extend upwardly and at their upper ends are connected to, and communicate with the interior of, a central air chamber which is mounted above the knitting head of the machine and is in turn connected with the common source of air suction.
 7. A multifeed circular knitting machine according to claim 6, wherein the central air chamber is of truncated conical form, being closed at its underside with a leakproof bottom cover into which the upper ends of the air-conducting pipes are fitted, the upper end of said chamber having a hollow boss onto which is fitted a pipe connected with the common source of air suction.
 8. A multifeed circular knitting machine according to claim 7, wherein the said pipe is connected by hoses with an air fan unit which is driven by a coaxial electric motor mounted on the machine. 